Limited range for PAW traffic - hardware issue?

[GeoffreyC]

First thing to ensure is that the antenna is completely in the clear. After that it may be worth trying another bridge board.

Thanks guys for your suggestions and comments.  I have removed the extension cable from the PAW and re-attached the PAW antenna directly to the PAW (that's currently velcro'd on top of the battery under the nose cone).  When I next go flying I will try it again.

On the power supply itself, ... I will rectify and fly PAW with the sole device on the Anker ...

Geoffrey

Update on my PAW limited range problems ...

I have now wired in a separate dedicated Anker Powerdrive 2 and now only run PAW from this with a 50cm 20AWG connector cable.

The PAW antennae extension cable has been removed and the PAW antennae directly connected to the bridge board and Brian Montilla kindly lent me a spare PAW bridge board so I've been trying it out on a couple of flights to see if these changes together fix my problems.

The short answer is no, I'm not convinced that it entirely has.  With Brian's bridge board in my classic I have been able to see other traffic up to the side of my flight path a maximum of 8 miles away, which is better than I had, but whilst flying today following Jinx who has a Rosetta I found several times that the signal disappeared after about a mile to mile and a half separation.

I appreciate that antennae positioning and attenuation can have a significant effect on signal strength, so its either that I need to extend the antennae again on a pigtail lead, or its the antennae itself that is the root cause of my problems.  My PAW classic is currently mounted on top of the battery on the QuikR base tube,  so its underneath the flexwing front pod.  The antennae is connected straight to the PAW, no extension lead, so is in front of me and behind the glass cockpit and all its electronics.
Although its not connected to any metal parts I am wondering whether the electronics up front is part of the problem and I need to get a pigtail and mount the PAW antennae under the QuikR windscreen or underneath the pod where it can get more 'clear air'?

If so, is there a recommended source of SMA M/F low loss extension leads?

Thanks, Geoffrey

[Vic]

Just like electrics is understandable in a plumbing sense, RF engineering can be related as low frequency light!...

Envisage a transmitting RF antenna as being a point of light source, or in the case of our dipole, a light stick.   Anything metallic in its vicinity  is going to cast a shadow and absorb some of the 'light'. In a perfect world, we want no shadows, or at least the smallest possible. This is acheived by keeping the light source as far away from parallel metal parts as best as possible.   

Obviously this isn't easy if you cannot install the antenna outside of the aircraft, so finding the best location to allow the most 'light' to get out (and in) for the job you want it to do is still an element of trial and error but using the above analogy is good as a starting point!

[Deker]

With Brian's bridge board in my classic I have been able to see other traffic up to the side of my flight path a maximum of 8 miles away, which is better than I had, but whilst flying today following Jinx who has a Rosetta I found several times that the signal disappeared after about a mile to mile and a half separation.

Hello Geoffrey,

Did Jinx loose your position at approximately the same range (1 to 1.5miles)  or were you visible on his display at a greater range?

Deker

[GeoffreyC]

With Brian's bridge board in my classic I have been able to see other traffic up to the side of my flight path a maximum of 8 miles away, which is better than I had, but whilst flying today following Jinx who has a Rosetta I found several times that the signal disappeared after about a mile to mile and a half separation.

Hello Geoffrey,

Did Jinx loose your position at approximately the same range (1 to 1.5miles)  or were you visible on his display at a greater range?

Deker

I didn't check with Jinx,  but from when I tried range checks with Brian on a previous flight,  we lost each other at about the same time.

Geoffrey

[exfirepro]

Geoffrey,

That sounds very like simple screening to me - this is very common to the rear with flexwings due to a combination of ‘non RF friendly’ objects - Pilot/passenger/luggage/pylon/engine/radiator/trike suspension/etc. getting between the antennas and the ‘targets’. 3-axis get a similar problem to the front and below due to the firewall and engine, hence why we normally suggest the coaming or underneath for their antennas.

Our priority is generally early warning to the front (highest closing speed) and trying to optimise antenna positioning to get as good to the rear as we are able, relying on incoming aircraft from the rear being picked up before they get into any ‘blind spot’.

I have done considerable experimentation with antenna types and positions to try to minimise these effects, with varying results. Fitting ‘horn-dipole type’ antennas up the sides of the trike windscreen is pretty effective. I have also tried standard PAW/Rosetta end fed (sleeve) dipoles in the same positions on 0.5m, 0.75m or even 1metre SMA extension cables. (I made up my own cables, but you can buy them from www.wifi-Antennas.co.uk - just be careful to specify SMA Male to SMA Female - NOT RP (Reverse Polarity) SMA - which are for WiFi Routers.)

I am currently testing a set of PAW ‘Rohan External Antennas’ mounted underneath the back edge of my fibreglass pod, with a plastic laminated aluminium foil ‘ground plane’ inside - under the pod bag, which so far seem to be giving positive results. I can, however, only fit the antennas in this position because my transponder antenna (which would otherwise overwhelm the 1090 Receiver) is fitted right at the back of my ‘skirt’. This installation seems to be bearing fruit so far, but I only fitted them last Thursday and testing so far has been limited to a weekend flight through to Gigha and back. First impressions, however are good, but it’s early days - I need to do more testing.
 
Best Regards

Peter

[GeoffreyC]

Geoffrey,

That sounds very like simple screening to me - this is very common to the rear with flexwings ...

I have done considerable experimentation with antenna types and positions to try to minimise these effects, with varying results. Fitting ‘horn-dipole type’ antennas up the sides of the trike windscreen is pretty effective. I have also tried standard PAW/Rosetta end fed (sleeve) dipoles in the same positions on 0.5m, 0.75m or even 1metre SMA extension cables. (I made up my own cables, but you can buy them from www.wifi-Antennas.co.uk - just be careful to specify SMA Male to SMA Female - NOT RP (Reverse Polarity) SMA - which are for WiFi Routers.)

Peter

Thanks Peter,

I agree, it sounds potentially like shielding, and with a flexwing you have limited places to put things.   Brian has his PAW antenna on the pod nose, in place of the radio antennae that used to be mounted there.  I don't like that option as its something to catch the bar on when de-rigging the wing off the trike (unlike your luxury hangar in East Fortune we are all semi-rigged at Sandy).

I have a short SMA MF antennae extension lead so will try putting the PAW dipole under the windscreen and see what that does for me.   Agree with your comment about prioritising oncoming traffic and the RF shielding that occurs with engine/people if you're  flying behind,  I'd just like it if I can get more than a mile or so of range.   With the antennae inside the nose pod behind the glass screen electronics I felt it wasn't ideal but was trying to eliminate other cause of my problem by going for a vanilla installation. 

Looking on wifi-antennas they only appear to have a 1m standard cables https://www.wifi-antennas.co.uk/1-metre-extension-cable-standard-range-sma-male-to-sma-female.html not low-loss ones.  eBay only had 16 foot long ones and Amazon 10-15cm.  I'll try with the one I've got and see what happens.

Geoffrey

[exfirepro]

Looking on wifi-antennas they only appear to have a 1m standard cables https://www.wifi-antennas.co.uk/1-metre-extension-cable-standard-range-sma-male-to-sma-female.html not low-loss ones.  eBay only had 16 foot long ones and Amazon 10-15cm.  I'll try with the one I've got and see what happens.

Geoffrey

Geoffrey,

Those ‘Standard Cables’ are made from CLF200 coax, which is pretty low-loss at PAW frequency  - well below 0.5dB per metre at 869MHz, so certainly worth a try in 1m or even 2m lengths. They will also make them for you in custom lengths, though the price will of course be dearer.

Let us know how you get on.

Regards

Peter

[GeoffreyC]

I have a short SMA MF antennae extension lead so will try putting the PAW dipole under the windscreen and see what that does for me.

I’ve mounted the PAW antennae under the lower front windscreen with my eBay extension lead.

Unfortunately no-one else with PAW active when I went flying on Saturday so wasn’t able to test the effectiveness of this setup.  Did see a couple of ground stations so I know its working.

Will try again with more aircraft !

Geoffrey